Water-repellent fabric and preparation method therefor

ABSTRACT

Disclosed are a water-repellent fabric and a preparation method therefor. A short carbon chain fluoroalkyl alcohol with different fluorine atom numbers used as a starter is firstly treated with an acylation reagent to generate a short carbon chain fluoroalkyl bromoacetate, and is then synthesized with N,N-bis(p-toluenesulfonyl) hydrazine to form a short carbon chain fluoroalkyl diazoacetate monomer, a fabric is respectively treated with an acylation reagent and N,N″-dimethylbenzenesulfonyl hydrazide in sequence to prepare a diazotized fabric having grafting sites on the surface thereof, and finally, a fluorine-containing polymer having a single carbon repeating unit is grafted to the surface of the fabric via a covalent bond by means of carbene polymerization, and thus a hydrophobic modified fabric is prepared. The entire reaction is carried out at a low temperature/room temperature, the operation is simple, and the process is environmentally friendly.

TECHNICAL FIELD

The invention relates to a water-repellent fabric and its preparation method, in particular to a covalent grafting fluoropolymer by carbene polymerization to construct low surface energy roughening structures with geometrical morphologies on the fiber surface, belonging to the technical field of special functional textiles and their preparation.

BACKGROUND OF INVENTION

With the continuous development of composite materials, the functional textile materials in China are still in the initial stage of development, but the development space is very large and the additional value is quite high, which makes it become a hot spot of material development in recent years. Fabric fiber is a kind of material with large specific surface area, and the surface modification of fiber material has become the main method to prepare these functional materials, especially in the field of preparation of waterproof and oil-repellent textiles. At present, the main methods of preparing water-repellent fabrics include impregnation coating method, spraying method, sol-gel method and gas/liquid deposition method, etc., but the hydrophobic effect on the surfaces of modified fabrics prepared by these methods is easily weakened or lost.

Covalent grafting is a rapidly developed and effective chemical modification method in recent years. Because low surface energy and certain roughness are the necessary conditions to obtain water-repellent surface, covalent grafting is generally to construct an active site on the fiber surface or to use the functional group of the fiber itself to graft the low surface energy polymer to the fabric through covalent bond, or some monomers containing low surface energy elements directly make polymerization reaction at the grafting site on the fiber surface to produce low surface energy polymers. However, due to the flexibility among the molecular chains of the traditional carbene polymers (C₂ polymers), it tends to form a film rather than roughening structures with uniform morphology after grafting on the surface of fabrics.

SUMMARY OF THE INVENTION Technical Problems

The present invention aims at the disadvantages of poor fastness, certain damage to the fiber itself and the need for multi-step organic-inorganic hybridization in the preparation of water-repellent functional fabrics by the impregnation coating method, and the problem that the low surface energy polymer grafted on the surface of the fabric by the traditional carbene polymerization covalent grafting method can not produce the roughening structures with geometrical morphologies, and discloses a method for preparing water-repellent fabric by covalent grafting fluoropolymer by carbene polymerization. The grafted short fluorine chain fluoroalkyl segmer has a good shielding effect on the main chain of the polymer by using the characteristics of single-carbon repetition of carbene polymer, that is, when the surface of the fabric is covalently grafted, the polymer growth of the monomer of only one carbon unit is provided in each chain propagation link. Under the induction of the surface of fibers, the carbene fluoropolymer grafted on the surface of the fabric forms low surface roughening structures with geometrical morphologies, which effectively improved the water repellency of the fabric.

Solutions to the Problems Technical Solution

The present invention constructs low surface energy roughening structures with geometrical morphologies on the surface of the fabric by means of carbene polymerization covalent grafting, and then produces a water-repellent fabric, whose chemical formula is shown below.

R is H or R′, m and n are repeating units, which are conventional representations; the surface of the covalently grafted fiber by means of carbene polymerization has a micro/nano-scale low surface energy polymer crystal roughening structures with uniform morphology and controllable size.

The technical solution to achieve the purpose of the present invention is.

A water-repellent fabric comprises a fabric and a covalently grafted fluorine-containing polymer by carbene polymerization on the surface of the fabric; the structural formula of the covalent grafting fluoropolymer by carbene polymerization is as follows.

Rf is fluoroalkyl; preferably, the fluorine atom number of the fluoroalkyl is 3-15.

The present invention discloses the application of the water-repellent fabric in the preparation of waterproof materials.

The preparation method of the water-repellent fabric includes the following steps: under the action of a catalyst, placed the fluoroalkyl diazoacetate and the active fabric in an organic solvent, and the fluoropolymer is covalently grafted to the fiber surface of the fabric by means of carbene polymerization to obtain the water-repellent fabric; the active fabric is a fabric containing grafting sites.

In the present invention, the fluorine atom number in fluoroalkyl diazoacetate is 3-15; the grafting site is diazo; the catalyst is palladium chloride; the organic solvent is one or more of tetrahydrofuran, dichloromethane and ethanol; the carbene polymerization is carried out under oscillation or stirring.

In the present invention, the fluoroalkyl alcohol reacts with bromoacetyl bromide to obtain fluoroalkyl bromoacetate, and then fluoroalkyl bromoacetate reacts with N,N″-dimethylbenzenesulfonyl hydrazide to obtain fluoroalkyl diazoacetate; the fabric is acylated and then reacted with N,N″-dimethylbenzenesulfonyl hydrazide to prepare the active fabric; and the reaction of fluoroalkyl alcohol and bromoacetyl bromide is carried out in the presence of alkali; the reaction of fluoroalkyl bromoacetate and N,N″-dimethylbenzenesulfonyl hydrazide is carried out in the presence of organic acid binding agent; the fluorine atom number of fluoroalkyl alcohol is 3-15.

The preparation method of the water-repellent fabric includes the following steps.

(1) Preparation of bromoacetate: To use fluoroalkyl alcohol as the starter, anhydrous tetrahydrofuran as the reaction medium, and react with bromoacetyl bromide under the action of sodium bicarbonate for substitution reaction to generate fluoroalkyl bromoacetate.

(2) Preparation of diazotate: To dissolve fluoroalkyl bromoacetate and diazo precursor N,N″-dimethylbenzenesulfonyl hydrazide in anhydrous tetrahydrofuran solvent to generate fluoroalkyl diazoacetate under the catalytic reaction of DBU.

(3) Preparation of grafting sites on the surface of fibers: To use tetrahydrofuran as solvent, and the surface groups of the fabric fiber are first acylated by acylating agent under the action of acid-binding agent, and then reacted with diazo precursor N,N″-dimethylbenzenesulfonyl hydrazide at room temperature to prepare the active fabric containing grafting sites.

(4) Carbene polymerization covalent grafting: Placing the fluoroalkyl diazoacetate and active fabric in the organic solvent, and under the action of catalyst, the polymer crystal roughening structures with geometrical morphology and size can be prepared on the surface of the fiber by carbene polymerization under different conditions.

In step (1) of the preparation method of the above water-repellent fabric, the fluoroalkyl alcohol is 3,3,3-trifluoro-1-propanol, perfluorobutyl ethanol, perfluorohexyl ethanol, etc; the temperature of the substitution reaction is −5˜5° C., preferably 0˜5° C.; the time of substitution reaction is 3˜5 h.

In step (2) of the preparation method of the above water-repellent fabric, the temperature of the catalytic reaction is −5˜5° C., preferably −5˜0° C.; the time of catalytic reaction is 3˜5 h.

In step (3) of the preparation method of the above water-repellent fabric, the acid-binding agent is any of sodium carbonate, potassium carbonate, sodium bicarbonate or potassium bicarbonate. The time of the room temperature reaction is 12-24 h.

In step (4) of the preparation method of the above water-repellent fabric, the catalyst is any of palladium chloride, palladium acetate, allyl palladium chloride (II) bipolymer or bis (acetonitrile) palladium chloride (II); the organic solvent is any one or mixed solvents of anhydrous tetrahydrofuran, anhydrous dichloromethane, ethanol, etc; the carbene polymerization reaction is carried out under the conditions of oscillation, stirring, etc., preferably vibration; the temperature of carbene polymerization is 25˜35° C., preferably 28˜32° C.; the reaction time of carbene polymerization is 12-24 h. Oscillation generally refers to the movement of the fabric with the conical bottle; stirring generally refers to the movement of the fabric, while the conical bottle does not move.

BENEFICIAL EFFECTS OF THE INVENTION Beneficial Effects

Compared with the prior art, the beneficial effects of the technical scheme provided by the invention are as follows:

1. The chemical modification method of covalent grafting is adopted: it takes the hydrophilic polar group of the fiber surface itself, such as hydroxyl, as the active grafting site to make chemical grafting reaction of the surface modifier and the active group, which not only reduces the hydrophilic group of the fiber surface, but also introduces the low surface energy functional polymer. Compared with the traditional method, the chemical covalent grafting method at room temperature of the present invention not only makes the water repellency of the modified fabric effective and durable, but also reduces the original performance of the fabric material to the minimum.

2. Carbene polymerization, a new single-carbon repeated polymerization method, makes the fluorine-containing side chains on the main chain of the grafted polymer closely accumulate and a small amount of short carbon chain fluoroalkyl monomers can produce a good shielding effect on the main chain of the polymer. The whole process of polymerization is carried out at room temperature, avoiding the potential danger caused by heating during the preparation and treatment of materials. And the by-product of polymerization is nitrogen, which does not require the treatment of tail gas and is relatively environmentally friendly.

3. It uses the single-carbon repetition and tridimensional regularity characteristics of a carbene polymer to construct low surface energy polymer roughening structures on the surface of the fabric in one step, which overcomes the complexity of multi-step modification of traditional organic-inorganic hybridization. This “bottom-up” modification method can achieve the required geometrical roughening morphology structure by designing the precursor molecular structure and changing the process, and can achieve uniform morphology and controllable size, overcoming the defect of singleness of inorganic micro/nano-scale particle roughening morphology.

BRIEF DESCRIPTION OF ATTACHED DRAWINGS Brief Description of the Drawings

FIG. 1 is the micrograph of the surface of fabric after carbene polymerization grafting prepared in Example 1.

FIG. 2 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 2.

FIG. 3 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (24 hours) in Example 2.

FIG. 4 is the micrograph of the surface of fabric after carbene polymerization grafting prepared in Example 3.

FIG. 5 is the micrograph of the surface of fabric after carbene polymerization grafting prepared in Example 4.

FIG. 6 is the micrograph of the surface of fabric after carbene polymerization grafting prepared in Example 5.

FIG. 7 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 6.

FIG. 8 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (24 hours) in Example 6.

FIG. 9 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 7.

FIG. 10 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (24 hours) in Example 7.

FIG. 11 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 8.

FIG. 12 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (24 hours) in Example 8.

FIG. 13 shows the content and distribution of elements on of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 2.

FIG. 14 shows the adhesion and hydrophobicity of the fabric after carbene polymerization grafting prepared (12 hours) in Example 2.

FIG. 15 shows the content and distribution of elements on of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 7.

EXAMPLES OF THE INVENTION Examples of the Present Invention

In the present invention, the water-repellent fabric is formed on the surface of the fabric through fluorine-containing polymer by means of carbene polymerization covalent grafting.

The preparation method of the water-repellent fabric includes the following steps.

(1) Preparation of bromoacetate: To use short carbon chain fluoroalkyl alcohol containing certain fluorine atom number as the starter, anhydrous tetrahydrofuran as the reaction medium, and react with bromoacetyl bromide under the action of sodium bicarbonate for substitution reaction to generate short carbon chain fluoroalkyl bromoacetate.

(2) Preparation of diazotate: To dissolve short carbon chain fluoroalkyl bromoacetate and diazo precursor N,N″-dimethylbenzenesulfonyl hydrazide in anhydrous tetrahydrofuran solvent to generate short carbon chain fluoroalkyl diazoacetate under the catalytic reaction of acid-binding agent DBU.

(3) Preparation of grafting sites on the surface of fibers: To use tetrahydrofuran as solvent, and the surface hydroxyl groups of the fiber are first acylated by acylating agent under the action of acid-binding agent, and then reacted with diazo precursor N,N″-dimethylbenzenesulfonyl hydrazide to prepare the active fiber containing grafting sites.

(4) Carbene polymerization covalent grafting: Placing the short carbon chain fluoroalkyl diazoacetate and active fiber in the organic solvent, and under the action of catalyst, the polymer crystal roughening structures with different morphologies and sizes can be prepared on the surface of the fiber by carbene polymerization under different conditions.

The specific steps are as follows:

(1) Synthesis of short carbon chain fluoroalkyl bromoacetate.

Under the protection of nitrogen, take dehydrated tetrahydrofuran as the reaction medium. Put short carbon chain fluoroalkyl alcohol and sodium bicarbonate into a three-necked flask, and slowly added bromoacetyl bromide into the mixture dropwise at low temperature (feeding proportion of 1:1.5:3 mol) for reaction. After the reaction, make quenching reaction with deionized water, then added saturated sodium bicarbonate solution, extract with dichloromethane, drying with anhydrous magnesium sulfate, to obtain the product by removing the low boiling point solvent by means of suction filtration and rotary evaporation.

(2) Synthesis of short carbon chain fluoroalkyl diazoacetate.

Under the protection of nitrogen, take dehydrated tetrahydrofuran as the reaction medium and added short carbon chain fluoroalkyl bromoacetate and N,N-bis(p-toluenesulfonyl) hydrazine into a three-necked flask, and added DBU into the mixture dropwise at low temperature for reaction at constant temperature for a certain time (feeding proportion of 1:2:5 mol). After the reaction, make quenching reaction with deionized water, then added saturated sodium bicarbonate solution, extract with trichloromethane, drying with anhydrous magnesium sulfate, to obtain the product by removing the low boiling point solvent by means of suction filtration and rotary evaporation.

(3) Generation of grafting sites on the fiber surface.

Under the protection of nitrogen, take dehydrated tetrahydrofuran as the reaction medium, added sodium bicarbonate and cotton fabric into the conical flask, added bromoacetyl bromide dropwise at low temperature, and then placing it at normal temperature for reaction. After the reaction, cleaning the fabric with tetrahydrofuran and deionized water respectively, and drying at low temperature. Then putting the dried fabric and N,N-bis(p-toluenesulfonyl) hydrazine into the reactor, and added DBU dropwise into the mixture at low temperature for reaction at constant temperature. After the reaction, cleaning the fabric with tetrahydrofuran and deionized water respectively, and drying at low temperature for standby.

(4) Covalent grafting fluorine-containing polymer to fiber surface by carbene polymerization

Under the protection of nitrogen, taking dehydrated tetrahydrofuran, dichloromethane, toluene, and the mixture of dehydrated tetrahydrofuran and anhydrous ethanol as the reaction media. Placing the monomer, active fiber and NaBPh₄ in a conical flask containing reaction media at room temperature, added (π-allylPdCl)₂ at low temperature, and then react at constant temperature under stable dynamic mode. After the reaction, cleaning the cotton fabric with tetrahydrofuran and deionized water respectively, and drying at low temperature to obtain water-repellent fabric.

The raw materials involved are all commercially available conventional products, and the fabric is conventional cotton fabric subject to conventional alkaline treatment; the specific operation method and test method are conventional techniques. With reference to the accompanying drawings and Example, the technical scheme of the present invention will be described in detail. Pretreatment of cotton fabric: at room temperature, immersing the conventional cotton fabric in sodium hydroxide solution with mass fraction of 20% for 25 min, washing it with distilled water three times, immersing it in 5% glacial acetic acid for 30 min, washing it to neutral with deionized water and drying to obtain alkalized cotton fabric to be used in.

Example 1

(1) Synthesis of trifluoropropyl diazoacetate:

Added 50 mL of anhydrous tetrahydrofuran, 0.57 g of 3,3,3-trifluoro-1-propanol and 1.26 g of sodium bicarbonate into a three-necked flask and cold it to 0° C. Under nitrogen dropped 1.54 g of bromoacetyl bromide in at constant temperature for 3 h. After the reaction, quenched with deionized water, then added saturated sodium bicarbonate solution, extracted with dichloromethane, dried with anhydrous magnesium sulfate, and to obtain 1.17 g of intermediate trifluoropropyl bromoacetate, with a yield of 89% by removing the low boiling point solvent by means of suction filtration and rotary evaporation. Put the prepared intermediate into a three-necked flask containing 60 mL of anhydrous tetrahydrofuran, added 3.41 g of N,N-bis(p-toluenesulfonyl) hydrazine and cold it to 0° C., and added 3.82 g of DBU dropwise into the mixed solution under nitrogen for reaction for 3 h. After the reaction, make quenching reaction with deionized water, then added saturated sodium bicarbonate solution, extract with dichloromethane 3 times, dried with anhydrous magnesium sulfate, to obtain 0.68 g product with a yield of 75% by removing the low boiling point solvent by means of suction filtration and rotary evaporation.

(2) Generation of grafting sites on the fiber surface: put 0.815 g of cotton fabric into a conical flask containing 50 mL of anhydrous tetrahydrofuran and 1.68 g of sodium bicarbonate, cold it to 0° C., added 1.68 g of bromoacetyl bromide under nitrogen for reaction at constant temperature for 30 min, and then put it in a shaker bath to naturally raise the temperature to 30° C. for reaction at constant temperature for 15 hours, and then washed it with tetrahydrofuran and deionized water respectively, and dried it to obtain brominated fabric. Immersed the brominated fabric in a conical flask containing anhydrous tetrahydrofuran, added 5.11 g of N,N-bis(p-toluenesulfonyl) hydrazine, cold it to 0° C., added 4.57 g of DBU under nitrogen, and react at 0° C. for 30 min, finally placed it in a shaker bath to naturally raise the temperature to 30° C. for oscillatory reaction at constant temperature for 20 hours. After the reaction, cleaned the fabric having grafting sites with tetrahydrofuran and deionized water respectively, and dried it for step (3).

(3) Preparation of hydrophobic fabric: Added 5 mmol of the synthesized trifluoropropyl diazoacetate into a conical flask containing 60 mL of anhydrous tetrahydrofuran, immersed the fabric having grafting sites into the flask, added 9.15 mg (π-allylPdCl)₂, then cold to −10° C., and added 32.5 mg of NaBPh₄. Moved the conical flask into the shaker bath at 0° C. for oscillatory reaction for 1 h, then raise the temperature to 10° C. for reaction for 1 h, raise the temperature to 20° C. for reaction for 1 h, and finally raise the temperature to 30° C. for reaction for 24 h. After the reaction, cleaned the fabric of graft polymer with ethanol and deionized water respectively, and dried it at 50° C. to obtain the water-repellent fabric.

Adjusted the above final reaction at 30° C. for 24 h to the reaction at 30° C. for 12 h, and kept the other conditions unchanged to obtain the water-repellent fabric.

(4) Contact angle test: used the OCAH200 Microscopic Droplet Wettability Tester from American Dataphysics to test the wettability of the grafted functional fabric, selected water as the test droplet, and the volume of the droplet was 5 μL and taken the average of five tests.

Example 2

(1) Synthesis of nonafluorohexyl diazoacetate: added 50 mL of anhydrous tetrahydrofuran, 1.32 g of perfluorobutyl ethanol and 1.26 g of sodium bicarbonate into a three-necked flask and cold it to 0° C., Added 1.54 g of bromoacetyl bromide under nitrogen, and make purification at constant temperature for 3 h to obtain 1.75 g of intermediate nonafluorohexyl diazoacetate. Then put the prepared intermediate into a three-necked flask containing 60 mL of anhydrous tetrahydrofuran, added 3.41 g of N,N-bis(p-toluenesulfonyl) hydrazine and cold it to 0° C., and added 3.82 g of DBU dropwise into the mixed solution under nitrogen for reaction for 3 h. After the reaction, make quenching reaction with deionized water, extract with dichloromethane 3 times, dried with anhydrous magnesium sulfate, to obtain 1.29 g product with a yield of 78% by removing the low boiling point solvent by means of suction filtration and rotary evaporation.

(2) Generation of grafting sites on the fiber surface: Consistent with the Example 1.

(3) Preparation of hydrophobic fabric: Added 5 mmol of the synthesized nonafluorohexyl diazoacetate in step (1) into a conical flask containing 60 mL of anhydrous tetrahydrofuran, immersed the fabric having grafting sites into the flask, added 9.15 mg (π-allylPdCl)₂, then put it in a low-temperature reactor and cold to −10° C., and added 32.5 mg of NaBPh₄. Moved the conical flask into the shaker bath at 0° C. for slow oscillation for 1 h, then react for 1 h at 10° C., react for 1 h at 20° C., and react for 24 h at 30° C. After the reaction, cleaned the fabric of graft polymer with ethanol and deionized water respectively, and dried it at 50° C.

Adjusted the above final reaction at 30° C. for 24 h to the reaction at 30° C. for 12 h, and kept the other conditions unchanged to obtain the water-repellent fabric.

(4) Contact angle test: used the OCAH200 Microscopic Droplet Wettability Tester from American Dataphysics to test the wettability of the grafted functional fabric, selected water as the test droplet, and the volume of the droplet was 5 μL and taken the average of five tests.

Example 3

(1) Synthesis of nonafluorohexyl diazoacetate: Consistent with the Example 2.

(2) Generation of grafting sites on the fiber surface: Consistent with the Example 1.

(3) Preparation of hydrophobic fabric: Added 5 mmol of the synthesized nonafluorohexyl diazoacetate in step (1) into a round-bottom flask containing 60 mL of anhydrous tetrahydrofuran, fixed the fabric having grafting sites on the bottom of the stirring paddedle and immersed it into the flask, added 9.15 mg (π-allylPdCl)₂, then put it in a low-temperature reactor and cold to −10° C., and added 32.5 mg of NaBPh₁₂; react for 1 h at 0° C. under dynamic stirring (fabric rotation, strength similar to that in Example 2, then reacted for 1 h at 10° C., reacted for 1 h at 20° C., and reacted for 12 h at 30° C. After the reaction, cleaned the fabric of graft polymer with ethanol and deionized water respectively, and dried it at 50° C.

(4) Contact angle test: used the OCAH200 Microscopic Droplet Wettability Tester from American Dataphysics to test the wettability of the grafted functional fabric, selected water as the test droplet, and the volume of the droplet was 5 μL and taken the average of five tests.

Example 4

(1) Synthesis of nonafluorohexyl diazoacetate: Consistent with the Example 2.

(2) Generation of grafting sites on the fiber surface: Consistent with the Example 1.

(3) Preparation of hydrophobic fabric: Added 5 mmol of the synthesized nonafluorohexyl diazoacetate in step (1) into a conical flask containing 60 mL of anhydrous toluene, immersed the fabric having grafting sites into the flask, added 9.15 mg (π-allylPdCl)₂, then put it in a low-temperature reactor and cold to −10° C., and added 32.5 mg of NaBPh₄. Moved the conical flask into the shaker bath at 0° C. for slow oscillation for 1 h, then reacted for 1 h at 10° C., reacted for 1 h at 20° C., and reacted for 24 h at 30° C. After the reaction, cleaned the fabric of graft polymer with ethanol and deionized water respectively, and dried it at 50° C.

Adjusted the above final reaction at 30° C. for 24 h to the reaction at 30° C. for 12 h, and kept the other conditions unchanged to obtain the water-repellent fabric.

(4) Contact angle test: used the OCAH200 Microscopic Droplet Wettability Tester from American Dataphysics to test the wettability of the grafted functional fabric, selected water as the test droplet, and the volume of the droplet was 5 μL and taken the average of five tests.

Example 5

(1) Synthesis of nonafluorohexyl diazoacetate: Consistent with the Example 2.

(2) Generation of grafting sites on the fiber surface: Consistent with the Example 1.

(3) Preparation of hydrophobic fabric: Added 5 mmol of the synthesized nonafluorohexyl diazoacetate in step (1) into a conical flask containing 60 mL of anhydrous dichloromethane, immersed the fabric having grafting sites into the flask, added 9.15 mg (π-allylPdCl)₂, then put it in a low-temperature reactor and cold to −10° C., and added 32.5 mg of NaBPh₄. Moved the conical flask into the shaker bath at 0° C. for slow oscillation for 1 h, then reacted for 1 h at 10° C., reacted for 1 h at 20° C., and reacted for 24 h at 30° C. After the reaction, cleaned the fabric of graft polymer with ethanol and deionized water respectively, and dried it at 50° C.

Adjusted the above final reaction at 30° C. for 24 h to the reaction at 30° C. for 12 h, and kept the other conditions unchanged to obtain the water-repellent fabric.

(4) Contact angle test: used the OCAH200 Microscopic Droplet Wettability Tester from American Dataphysics to test the wettability of the grafted functional fabric, selected water as the test droplet, and the volume of the droplet was 5 μL and taken the average of five tests.

Example 6

(1) Synthesis of nonafluorohexyl diazoacetate: Consistent with the Example 2.

(2) Generation of grafting sites on the fiber surface: Consistent with the Example 1.

(3) Preparation of hydrophobic fabric: Added 5 mmol of the synthesized nonafluorohexyl diazoacetate in step (1) into a conical flask containing 50 mL of anhydrous tetrahydrofuran and 10 mL of anhydrous ethanol mixture, immersed the fabric having grafting sites into the flask, added 9.15 mg (π-allylPdCl)₂, then put it in a low-temperature reactor and cold to −10° C., and added 32.5 mg of NaBPh₄. Moved the conical flask into the shaker bath at 0° C. for slow oscillation for 1 h, then reacted for 1 h at 10° C., reacted for 1 h at 20° C., and reacted for 24 h at 30° C. After the reaction, cleaned the fabric of graft polymer with ethanol and deionized water respectively, and dried it at 50° C.

Adjusted the above final reaction at 30° C. for 24 h to the reaction at 30° C. for 12 h, and kept the other conditions unchanged to obtain the water-repellent fabric.

(4) Contact angle test: used the OCAH200 Microscopic Droplet Wettability Tester from American Dataphysics to test the wettability of the grafted functional fabric, selected water as the test droplet, and the volume of the droplet was 5 μL and taken the average of five tests.

Example 7

(1) Synthesis of tridecafluorooctyl diazoacetate: added 50 mL of anhydrous tetrahydrofuran, 1.82 g of perfluorohexyl ethanol and 1.26 g of sodium bicarbonate into a three-necked flask and cold it to 0° C. Added 1.54 g of bromoacetyl bromide under nitrogen, and make reaction at constant temperature for 3 h to obtain 2.09 g of intermediate tridecafluorooctyl diazoacetate. Then put the prepared intermediate into a three-necked flask containing 60 mL of anhydrous tetrahydrofuran, added 3.41 g of N,N-bis(p-toluenesulfonyl) hydrazine and cold it to 0° C., and added 3.82 g of DBU under nitrogen for reaction for 3 h. After the reaction, make quenching reaction with deionized water, extract with dichloromethane 3 times, dried with anhydrous magnesium sulfate, to obtain 1.64 g product with a yield of 76% by removing the low boiling point solvent by means of suction filtration and rotary evaporation.

(2) Generation of grafting sites on the fiber surface: Consistent with the Example 1.

(3) Preparation of hydrophobic fabric: Added 5 mmol of the synthesized tridecafluorooctyl diazoacetate into a conical flask containing 60 mL of anhydrous tetrahydrofuran, immersed the fabric having grafting sites into the flask, added 9.15 mg (T-allylPdCl)₂, then cold to −10° C., and added 32.5 mg of NaBPh₄. Moved the conical flask into the shaker bath at 0° C. for slow oscillation for 1 h, then reacted for 1 h at 10° C., reacted for 1 h at 20° C., and reacted for 24 h at 30° C. After the reaction, cleaned the fabric of graft polymer with ethanol and deionized water respectively, and dried it at 50° C.

Adjusted the above final reaction at 30° C. for 24 h to the reaction at 30° C. for 12 h, and kept the other conditions unchanged to obtain the water-repellent fabric.

(4) Contact angle test: used the OCAH200 Microscopic Droplet Wettability Tester from American Dataphysics to test the wettability of the grafted functional fabric, selected water as the test droplet, and the volume of the droplet was 5 μL and taken the average of five tests.

Example 8

(1) Synthesis of tridecafluorooctyl diazoacetate: Consistent with the Example 7.

(2) Generation of grafting sites on the fiber surface: Consistent with the Example 1.

(3) Preparation of hydrophobic fabric: Added 5 mmol of the synthesized tridecafluorooctyl diazoacetate in step (1) into a conical flask containing 50 mL of anhydrous tetrahydrofuran and 10 mL of anhydrous ethanol mixture, immersed the fabric having grafting sites into the flask, added 9.15 mg (π-allylPdCl)₂, then put it in a low-temperature reactor and cold to −10° C., and added 32.5 mg of NaBPh₄. Moved the conical flask into the shaker bath at 0° C. for slow oscillation for 1 h, then reacted for 1 h at 10° C., reacted for 1 h at 20° C., and reacted for 24 h at 30° C. After the reaction, cleaned the fabric Polymer-cotton of graft polymer with ethanol and deionized water respectively, and dried it at 50° C.

Adjusted the above final reaction at 30° C. for 24 h to the reaction at 30° C. for 12 h, and kept the other conditions unchanged to obtain the water-repellent fabric.

(4) Contact angle test: used the OCAH200 Microscopic Droplet Wettability Tester from American Dataphysics to test the wettability of the grafted functional fabric, selected water as the test droplet, and the volume of the droplet was 5 μL and taken the average of five tests.

FIG. 1 is the micrograph of the surface of fabric after carbene polymerization grafting prepared in Example 1, and the generated rod-like roughening structures evolve to local hollow tubular structures with time, and the contact angle to water is less than 100°.

FIG. 2 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 2, and the generated micron-sized rod-like roughening structures are uniformly covered with high grafting rate, and the contact angle to water is 146°.

FIG. 3 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (24 hours) in Example 2, and the generated micron-sized tubular roughening structures are uniformly covered with high grafting rate, and the contact angle to water is 152°.

FIG. 4 is the micrograph of the surface of fabric after carbene polymerization grafting prepared in Example 3, and the micron-sized spherical/hemispherical roughening structures are generated, and the contact angle to water is 125°.

FIG. 5 is the micrograph of the surface of fabric after carbene polymerization grafting prepared in Example 4, and it shows the micron-sized rod-like roughening structures with better structural regularity and obvious rectangular cross section, and the contact angle to water is 132° (12 hours) and 135° (24 hours) respectively.

FIG. 6 is the micrograph of the surface of fabric after carbene polymerization grafting prepared in Example 5, and the rod-like roughening structures will eventually cross-link and aggregate with each other to form flaky structures and the contact angle to water is 135° (12 hours) and 138° (24 hours) respectively.

FIG. 7 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 6, and the generated uniformly dispersed nano-sized particles will gradually converge into micrometer-sized roughening particles, and the contact angle to water is 153°.

FIG. 8 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (24 hours) in Example 6, and the generated uniformly dispersed nano-sized particles will gradually converge into micrometer-sized roughening particles, and will further evolve into loose sheets and the contact angle to water is 148°.

FIG. 9 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 7, and the generated rod-like roughening structures with uniform coverage and high grafting rate do not evolve into tubular structures, and the contact angle to water is 145°.

FIG. 10 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (24 hours) in Example 7, and the rod-like roughening structures with uniform coverage and high grafting rate are generated, and it can be seen clearly that the fiber surface is covered with a layer of rod-like crystal structure with uniform morphology and size, and the contact angle to water is 151°.

FIG. 11 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 6, and the generated nano-sized particles will aggregate into micrometer-sized roughening structures, and eventually evolve into larger aggregate particles, and the contact angle to water is 152°.

FIG. 12 is the micrograph of the surface of fabric after carbene polymerization grafting prepared (24 hours) in Example 6, and the generated nano-sized particles will aggregate into micrometer-sized roughening structures, and eventually evolve into larger aggregate particles, and the new nano particles grow again on the large micron surface of the accumulation and the contact angle to water is 154°.

FIG. 13 shows the content and distribution of elements on of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 2.

FIG. 14 shows the adhesion and hydrophobicity of the fabric after carbene polymerization grafting prepared (12 hours) in Example 2.

The adhesion between the solid surface and the liquid droplet is one of the important parameters to measure the anti-wettability function of the fabric. The chemical composition of the solid surface not only affects the static contact angle, but also has a considerable impact on the dynamic adhesion. The adhesion of the surface to water is different for either the highly hydrophobic or super-hydrophobic surface. In the adhesion curve, the adhesion of the surface of raw cotton fabric to water is more than 140 uN, while it can be seen from FIG. 14 that the adhesion of the fabric to water is 64 uN after the carbene polymerization grafting by nonafluorohexyl diazoacetate.

FIG. 15 shows the content and distribution of elements on of the surface of fabric after carbene polymerization grafting prepared (12 hours) in Example 7.

The invention discloses a water-repellent fabric, which expands the application research of carbene polymerization in the field of preparation of functional materials. Based on the single-carbon repetition and tridimensional regularity characteristics of a carbene polymer, the novel carbene polymerization covalent grafting can construct low surface energy roughening structures on the surface of the fabric in one step, which doesn't require the traditional organic-inorganic hybridization and multi-step reaction and can obtain the relatively durable hydrophobic effect. The novel carbene polymerization (C₁ polymerization) can graft the low surface energy polymer based on the single carbon repeating unit to the cotton fabric, and utilizes the molecular chain rigidity of the densely stacked single carbon units, so it is expected to induce the carbene polymer crystallization on the fiber surface to form polymer crystal structures with roughening morphologies on the surface of fabric by self-assembly driven by crystallization, thus obtaining the required protective physical structures. The process of carbene polymerization grafting is carried out at low/room temperature. Compared with other modification methods that need to be carried out at high temperature/high pressure or under strong acid/alkali or strong oxidant conditions, it achieves the minimum damage to the fiber and the by-product of polymerization is nitrogen, which is relatively environmentally friendly. 

1. A water-repellent fabric, wherein: the water-repellent fabric comprises a fabric and a covalent grafting fluoropolymer by carbene polymerization on the surface of the fabric.
 2. The water-repellent fabric according to the claim 1, wherein: the structural formula of the covalent grafting fluoropolymer by carbene polymerization is as follows:

Rf represents fluoroalkyl.
 3. The water-repellent fabric according to the claim 2, wherein: a fluorine atom number of the fluoroalkyl is 3-15.
 4. The water-repellent fabric according to the claim 1 is applied in the preparation of waterproof materials.
 5. A preparation method of the water-repellent fabric according to the claim 1, wherein: the method comprises the following steps: under the action of a catalyst, place the fluoroalkyl diazoacetate and the active fabric in an organic solvent, and the fluoropolymer is covalently grafted to the fiber surface of the fabric by means of carbene polymerization to obtain the water-repellent fabric; the active fabric is a fabric containing a grafting site.
 6. The preparation method of the water-repellent fabric according to the claim 5, wherein: a fluorine atom number in the fluoroalkyl diazoacetate is 3-15; the grafting site is diazo.
 7. The preparation method of the water-repellent fabric according to the claim 5, wherein: the catalyst is palladium chloride; the organic solvent is one or more of tetrahydrofuran, dichloromethane and ethanol; the carbene polymerization is carried out under oscillation or stirring.
 8. The preparation method of the water-repellent fabric according to the claim 5, wherein: the fluoroalkyl alcohol reacts with bromoacetyl bromide to obtain fluoroalkyl bromoacetate, and then fluoroalkyl bromoacetate reacts with N,N″-dimethylbenzenesulfonyl hydrazide to obtain fluoroalkyl diazoacetate; the fabric is acylated and then reacted with N,N″-dimethylbenzenesulfonyl hydrazide to prepare the active fabric.
 9. The preparation method of the water-repellent fabric according to the claim 8, wherein: the reaction of fluoroalkyl alcohol and bromoacetyl bromide is carried out in the presence of alkali; the reaction of fluoroalkyl bromoacetate and N,N″-dimethylbenzenesulfonyl hydrazide is carried out in the presence of organic acid binding agent.
 10. The preparation method of the water-repellent fabric according to the claim 8, wherein: the fluorine atom number of the fluoroalkyl is 3-15. 